As a rule, in a radio communication network representing a mobile telephone network, a drive-test for performing a measurement within an area with a vehicle having a special-purpose measurement apparatus installed therein is performed for a purpose of investigating radio characteristics (a received quality of a radio wave coming from a radio base station and events such as a reception error and an access failure) within the area.
It is being investigated in a 3GPP (3rd Generation Partnership Project) to cause general radio terminals to measure/report information conventionally collected by drive-tests or information similar hereto so as to reduce operation cost (OPEX) that is needed for the drive-tests (Drive-Test) to be performed by operators (Non-patent literature 1). The final goal of this investigation is to minimize execution of the drive-tests (Minimization of Drive-Tests: MDT). In the feasibility study of the MDT, how the radio terminals are caused to measure the information and how the radio terminals are caused to report a log of the measurement results and the past measurement results are being discussed. Currently, the periodical reporting technique and the event triggered measurement reporting technique are specified. Additionally, what is herein called “the measurement” by the radio terminal also includes an operation of “detecting” some situations.
In the periodical technique, a radio network (for example, a radio base station) previously notifies a measurement interval and/or a report interval to the radio terminal, and the radio terminal performs the measurement and/or the reporting according hereto. Herein, as the periodic measurement, there exist, for example, periodical received quality measurements of downlink pilot signals (Periodical downlink pilot measurements) and the like.
In the technology of the Non-patent literature 1, the radio terminal periodically performs the received quality measurement of the downlink pilot signals of serving cells (Periodical downlink pilot measurements), and periodically reports the measurement result. Herein, the so-called received quality measurement of the pilot signals is equivalent to measuring the radio characteristics such as RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), CPICH RSCP (Common Pilot Channel Received Signal Code Power), and CPICH Ec/No (Ec: received energy per chip, No: Noise power density).
In addition, the radio terminal having a positioning function is instructed to periodically perform positioning (measurement of locations) as well and to report location information together with a measurement result of the above-mentioned radio characteristics.
The details of the Non-patent literature 1 will be explained with 3GPP LTE (Long Term Evolution) exemplified by referencing FIG. 15.
The radio terminal (UE: User Equipment) notifies a function the radio terminal itself supports to the radio base station (eNB: enhanced Node B) (UE capability report). For example, the radio terminal notifies whether or not the positioning function the radio terminal itself supports, for example, GPS (Global Positioning System) and OTDOA (Observed Time Difference Of Arrival) and the like are utilizable.
A radio network (EPC: Evolved Packet Core, for example, NM: Network Manager) notifies a measurement policy (Measurement policy) to the eNB (Policy indication), and the eNB gives an instruction for the measurement and the reporting to the UE according to the above policy (Measurement, logging and reporting configuration). Herein, it is assumed that the measurement and the reporting are performed at an interval T1 and at an interval T2, respectively.
The UE performs the received quality measurement of the downlink pilot signals (for example, the RSRP) and the positioning at the interval T1 according to the above policy, and maintains its measurement result as a measurement log(Measurement and logging). And, the UE reports the above measurement log to the eNB at the interval T2 (Measurement log report). In addition, the eNB reports the report coming from the UE to an upper NW (Log report).
Hereinafter, likewise, the UE repeats a series of the operations of the measurement—the logging—the reporting.
Herein, for determining a lapse of the interval T1/T2, for example, a timer is used. Further, the UE finishes the above series of the operations when a period or a number of times of the reports previously notified from the eNB is satisfied, or when an instruction is given by the eNB.
Additionally, in some cases, for not only a serving cell but also a neighboring cell, the received quality measurement of the downlink pilot signals is performed periodically.
On the other hand, in the event trigger technique, the radio network (for example, the radio base station) previously notifies the condition, being a trigger for the measurement and/or the reporting, to the radio terminal, and the radio terminal performs the measurement and/or the reporting when the above condition is satisfied. Herein, as the condition, being the trigger, there exist the radio characteristics such as a broadcast channel reception error (Broadcast Channel Failure), a paging channel reception error (Paging Channel Failure), the received quality of the serving cell becoming worse than a predetermined threshold (Serving Cell becomes worse than threshold), and a failure of a random access (Random access failure) (Non-patent literature 2). Additionally, the radio terminal reports information as well of the time when the trigger has occurred together with the measurement result.
In addition, the radio terminal having the positioning function is instructed to perform the positioning as well at a time point when the trigger has occurred, and to report location information.
In the technology of the Non-patent literature 2, the radio terminal performs the measurement when the event is triggered, stores the result of the measurement as the measurement log, and reports it when the event is triggered. For example, it is assumed that the condition under which the trigger of the measurement occurs is the paging channel reception error (Paging Channel Failure), and the radio terminal performs the received quality measurement of the downlink pilot signals of the serving cell and the positioning when the above condition is satisfied. Further, it is assumed that the condition under which the trigger of the reporting occurs is, for example, a time point when a predetermined amount of the measurement logs have been accumulated, and the radio terminal reports the measurement log to the radio network when the above condition is satisfied.
The details of the technology of the Non-patent literature 2 will be explained with the 3GPP LTE exemplified by referencing FIG. 16.
The UE notifies functions the UE itself supports to the eNB (UE capability report). For example, the UE notifies whether or not the positioning function the UE itself supports, for example, the GPS (Global Positioning System) and the OTDOA (Observed Time Difference Of Arrival) and the like are utilizable.
The EPC (for example, NM) notifies a measurement policy (Measurement policy) to the eNB (Policy indication), and the eNB gives an instruction for the measurement and the reporting to the UE according to the above policy (Measurement, logging and reporting configuration). Herein, as one example, it is assumed that the condition, being the trigger of the measurement is the paging channel reception error, and the trigger of the reporting is a time point when the amount of the measurement logs (a memory capacity of the terminal used for the measurement logs) has reached a predetermined value.
The UE periodically receives the paging channels, performs the received quality measurement (for example, the RSRP) of the downlink pilot signals of the serving cell and the positioning thereof according to the above instruction when the paging channel reception error (Paging Failure) occurs, and maintains its result together with the time of the occurrence of the paging channel reception error as the measurement log(Measurement and logging). And, when the amount of the measurement logs has reached a predetermined value, the UE reports the above measurement logs to the eNB (Measurement log report). In addition, the eNB reports the report coming from the UE to the upper NW (Log report).
Hereinafter, likewise, the UE repeats a series of the operations of the measurement—the logging—the reporting.
Herein, the UE finishes the above series of the operations when the UE is instructed to do so by the eNB.
Additionally, in some cases, for not only the serving cell but also the neighboring cell, the received quality measurement of the downlink pilot signals when the trigger of the measurement occurs is performed periodically.
Further, as the method of the positioning, the GPS (Global Positioning System) that performs the positioning using an artificial satellite orbiting over the earth, the OTDOA (Observed Time Difference Of Arrival) that performs the positioning based on a delay time of the radio wave that arrives from the radio base station, and the like are being investigated.